Gas leaking from carbs

[TheNannerpus]

I've been updating my intro post with progress on my bike here:

https://xs11.club/forum/idle-talk-fo...xs1100-special

I've run into a problem with gas leaking from my airbox, so I've pulled the carbs for the 3rd time 😬👍 in just a couple of weeks (I'm getting good at it). I checked float heights and they look good. #1 and #4 are a little strong at 23.5 mm (see pic), #2 and #3 are dead nuts. Measurements taken with gasket removed, on the nature flat part next to little ridge.

I decided I want to see how much gas is actually in each bowl so I hooked up my hanging gas tank with the carbs off the bike to see what happens. Gas leaked out of #2 carb, and possibly the air inlet - the hole at 4 o'clock position (see pic).

I also recorded the amount of gas in each bowl by draining them each into a jar and marking their levels. The pic shows them to be pretty even, but #2 does have a bit more, which is weird because it's measurement was the same as #3. I emptied it each time into a measuring cup to see the grand total, which was around 280ml. Is there a target amount I should see?

Any suggestions on what to do next?

[Schming]

This procedure in the link works the best

http://www.xs11.com/xs11-info/tech-t...balancing.html

[DiverRay]

Are you checking BOTH floats on each carb? All 8 floats should be EXACT in the measurement. If one carb is leaking, that is the one you need to look at! Check or replace the "O' rings on the valve seats if you have not already. Also, you can mount the carbs upside down in a vice, hook up the lines and verify that no gas will get past the needle/seat. Do NOT set the remote tank more than about 12" above the carbs for this test. If you have a bad casting, it should show up as gas weeping from someplace between the inlet and the seat.

[TheNannerpus]

This procedure in the link works the best

http://www.xs11.com/xs11-info/tech-t...balancing.html

Thanks for responding. I've come across this article in my research on this site. IMHO, what this article does not do is address its own goal: "accurate and sufficient fuel level in the float bowl."

What is the correct level of fuel in the bowl? That's a target I can def hit adjusting the floats. And that's why I included the pics showing gas levels and total amount of gas. If I were told "each bowl needs 75ml of gas" then I'm off to the races. Right now, I'm adjusting to avoid a fuel leak and I'm not sure that's going to give me the best outcome.

[TheNannerpus]

Are you checking BOTH floats on each carb? All 8 floats should be EXACT in the measurement. If one carb is leaking, that is the one you need to look at! Check or replace the "O' rings on the valve seats if you have not already. Also, you can mount the carbs upside down in a vice, hook up the lines and verify that no gas will get past the needle/seat. Do NOT set the remote tank more than about 12" above the carbs for this test. If you have a bad casting, it should show up as gas weeping from someplace between the inlet and the seat.

DiverRay

On these leaking ones, I am checking both sides of the float. They measure the same. I have replaced all parts using the kits recommended here (from georgefix on ebay), I think they're T&L if I recall, made in Japan.

The info that caught my eye was the height of my remote tank. I'm hanging it near the top of a 6' stepladder. Is that creating to much fuel pressure, and forcing gas out of the bowls?

As asked in my above response, what should the fuel height be in each bowl? I can connect hoses to the drains and see where that comes out, but I don't know the target.

[bikerphil]

what should the fuel height be in each bowl?

For the 81-82's, should be the same for 80's with the plastic floats.

[TheNannerpus]

Here's what I ended up doing.

Based on research here and other places, the most important measurement seems to be fuel level in the bowl rather than float height. 23.5mm is where I set all the floats, which is only .5mm strong, and it did stop the fuel leak. And now I can put down the fire extinguisher when I start it up. (Though it's still close by.)

The carb is back on the bike. I used my new carbtune to synch them, worked like a charm and evened out the idle (I'll add a video to my main thread).

I'll use bikerphil (thanks!) info to check levels while carbs are on the bike. Is that data good for '80 Special? Nevermind, I see you updated the post - thanks!

[Schming]

The ultimate goal is to reach the fuel level in Phil's post whilst the bike is running at idle, on the center stand, as level as possible.
Also the carbs should be in synch and mixture screws set properly.
These three tasks, once completed and rechecked will amaze you how smooth the bike will climb from 20mph in 5th gear to max speed without downshifting.

[Radioguylogs]

For the 81-82's, should be the same for 80's with the plastic floats.

I remember that picture and the words in the FSM seem to be a contradiction.

I think the 3mm is supposed to be measured from the top of the bowl where it joins the top half of the carb.

When you measure 3mm down form the top of the bowl, the correct level is right at the bottom surface of the washer (the washer on the float bowl screw).

Anybody else remember this discussion? Please chime in.

[Schming]

Yes Mike, I believe you're correct. That's where mine are set and the bike likes it

[cajun31]

Here's what I ended up doing.

Based on research here and other places, the most important measurement seems to be fuel level in the bowl rather than float height. 23.5mm is where I set all the floats, which is only .5mm strong, and it did stop the fuel leak. And now I can put down the fire extinguisher when I start it up. (Though it's still close by.)

The carb is back on the bike. I used my new carbtune to synch them, worked like a charm and evened out the idle (I'll add a video to my main thread).

I'll use bikerphil (thanks!) info to check levels while carbs are on the bike. Is that data good for '80 Special? Nevermind, I see you updated the post - thanks!

Good to see you got the fuel to stop leaking. Leave well enough alone if the bike is running right. The method bikerphil posted is not specifically intended for your 80 special. I have never used that method on any of my 81 or 80s. I just make sure the float levels are set right... they are synched... colortuned and synch checked again. Bikes run great at all throttle ranges.